Modal forms hidden by fsStayOnTop forms

Question

I have a form (TBigForm in the example below) which allows to manipulate some complex data and needs additional information to be shown. I put this info in a fsStayOnTop form (OnTopForm in the example) to ensure it's always visible but can be moved out of the way if necessary. Now when some user action in TBigForm shows a modal form this often gets hidden behind OnTopForm which makes the app look frozen. How can I avoid this? (Searching yields many, many hits but I wasn't able to distill a solution out of them.)

In my real app there are a lot of places where modal forms are shown, so I would like to avoid changing all of these calls.

Example: Create a new VCL application, drop a TButton on Form1, double-click the button and replace the generated Button1Click implementation stub with the following:

type
  TBigForm = class(TForm)
  strict private
    OnTopForm: TForm;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  protected
    procedure DoHide; override;
    procedure DoShow; override;
  public
    constructor Create(AOwner: TComponent); override;
  end;

{ TBigForm }

procedure TBigForm.Button1Click(Sender: TObject);
begin
  ShowMessage('Test');
end;

constructor TBigForm.Create(AOwner: TComponent);
begin
  inherited CreateNew(AOwner);

  Caption := 'Big form';
  WindowState := wsMaximized;

  Button1 := TButton.Create(Self);
  Button1.Parent := Self;
  Button1.Caption := 'Freeze!';
  Button1.SetBounds(10, 10, 100, 100);
  Button1.OnClick := Button1Click;
end;

procedure TBigForm.DoHide;
begin
  OnTopForm.Free;
  inherited DoHide;
end;

procedure TBigForm.DoShow;
begin
  inherited DoShow;
  OnTopForm := TForm.Create(Self);
  OnTopForm.Caption := 'Important information';
  OnTopForm.BorderStyle := bsToolWindow;
  OnTopForm.FormStyle := fsStayOnTop;
  OnTopForm.Position := poScreenCenter;
  OnTopForm.Show;
end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  f: TBigForm;
begin
  f := TBigForm.Create(nil);
  try
    f.ShowModal;
  finally
    f.Free;
  end;
end;

Start the app, click on "Button1" and then on "Freeze!".

(BTW: We use D2007.)

Answer 1

Change temporarily the FormStyle of your OnTopform before displaying another Form as Modal:

procedure TBigForm.Button1Click(Sender: TObject);
begin
  OnTopForm.FormStyle := fsNormal;
  ShowMessage('Test');
  OnTopForm.FormStyle := fsStayOnTop;
end;

It should work for what you want...

Answer 2

Try setting the modal Form's PopupParent property to be the StayOnTop Form, or set the Application.ModalPopupMode property to something other than pmNone, prior to calling ShowModal().